title: Direct measurement of perchlorate exposure biomarkers in a highly exposed population: a pilot study.
abstract: Exposure to perchlorate is ubiquitous in the United States and has been found to be widespread in food and drinking water. People living in the lower Colorado River region may have perchlorate exposure because of perchlorate in ground water and locally-grown produce. Relatively high doses of perchlorate can inhibit iodine uptake and impair thyroid function, and thus could impair neurological development in utero. We examined human exposures to perchlorate in the Imperial Valley among individuals consuming locally grown produce and compared perchlorate exposure doses to state and federal reference doses. We collected 24-hour urine specimen from a convenience sample of 31 individuals and measured urinary excretion rates of perchlorate, thiocyanate, nitrate, and iodide. In addition, drinking water and local produce were also sampled for perchlorate. All but two of the water samples tested negative for perchlorate. Perchlorate levels in 79 produce samples ranged from non-detect to 1816 ppb. Estimated perchlorate doses ranged from 0.02 to 0.51 µg/kg of body weight/day. Perchlorate dose increased with the number of servings of dairy products consumed and with estimated perchlorate levels in produce consumed. The geometric mean perchlorate dose was 70% higher than for the NHANES reference population. Our sample of 31 Imperial Valley residents had higher perchlorate dose levels compared with national reference ranges. Although none of our exposure estimates exceeded the U. S. EPA reference dose, three participants exceeded the acceptable daily dose as defined by bench mark dose methods used by the California Office of Environmental Health Hazard Assessment.
authors.affiliation: California Environmental Health Tracking Program, California Department of Public Health, Richmond, California, United States of America. penglish@dhs.ca.gov
authors.forename: Paul
authors.initials: P
authors.lastname: English
authors.forename: Ben
authors.initials: B
authors.lastname: Blount
authors.forename: Michelle
authors.initials: M
authors.lastname: Wong
authors.forename: Lori
authors.initials: L
authors.lastname: Copan
authors.forename: Luis
authors.initials: L
authors.lastname: Olmedo
authors.forename: Sharyle
authors.initials: S
authors.lastname: Patton
authors.forename: Robert
authors.initials: R
authors.lastname: Haas
authors.forename: Ryan
authors.initials: R
authors.lastname: Atencio
authors.forename: Juhua
authors.initials: J
authors.lastname: Xu
authors.forename: Liza
authors.initials: L
authors.lastname: Valentin-Blasini
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000652:urine; D003120:Colorado; D004781:Environmental Exposure / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods*; D005260:Female; D005638:Fruit / Q000737:chemistry; D005843:Geography; D006801:Humans; D008297:Male; D008875:Middle Aged; D010472:Perchlorates / Q000652:urine*; D010865:Pilot Projects; D045483:Rivers / Q000737:chemistry; D014675:Vegetables / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000652:urine; D014876:Water Pollution / Q000032:analysis; D014881:Water Supply / Q000032:analysis; D055815:Young Adult
chemical_list: D015415:Biomarkers; D010472:Perchlorates; D014874:Water Pollutants, Chemical; C494474:perchlorate